When irrigating extensive areas of land, long sprinkler lines have been used for some time. Water has been supplied to these lines from buried pipes called main lines with spaced risers projecting above the surface of the ground for connection to the sprinkler lines. Each time a sprinkler line had to be moved to a new riser, manual labor was required for this purpose. This was a laborious and time consuming operation. As time went on, the sprinkler lines, which can reach a length of a quarter of a mile and more were fitted with wheels to make them easier to move. Eventually, power was supplied in one way or another to the wheeled lines to keep them moving slowly along the desired path parallel to the direction of the main line with flexible hoses extending between the water inlet end of a sprinkler line and the riser to which the sprinkler line was connected. Since the main line can be eight or more inches in diameter with the water pressure in the main line high, the required size and strength of the flexible hoses became extremely burdensome in manual operation. Proposals were therefore made to facilitate connection of the sprinkling lines to successive risers with the least manual effort but to applicant's knowledge no successful machine has been developed prior to his. Three examples of such proposals are illustrated in Engel U.S. Pat. No. 2,740,228, Stafford U.S. Pat. No. Re. 26,285 and Smith et al U.S. Pat. Nos. 3,381,893 and 3,446,434. Such proposals provided for intermittent connection of the sprinkler line to the main line utilizing power assisted mechanical devices as the hoses or telescoping pipes were moved from riser to riser, with the sprinkler line continuing to move along at the desired rate.
In order to provide for a continual source of water to the sprinkler line Rogers U.S. Pat. No. 3,463,175, and Standal U.S. Pat. Nos. 4,036,436 and 4,172,556 proposed systems in which one riser is always connected to the sprinkler line, this being accomplished by having pipe or hose connections to the sprinkler line connect with devices which span three risers. By this arrangement, the forward part of the device is disconnected from one riser and goes on to a second riser ahead of the first riser and on connection of the device with the second riser, the hindmost part of the device, which has been connected to a third riser which is behind the first riser in the main line, moves up to connect with the first riser. As far as known to the applicant, these proposals were never put into use. In addition to requiring closely spaced risers, the mechanical problems associated with the disclosed systems appear to have ruled out their use.
Von Linsowe U.S. Pat. No. 3,729,016 discloses another form of system for continuously feeding the water to a sprinkler line, but this system is extremely complicated and requires trackways and twin main lines since the twin coupling devices for connecting the sprinkler line to the main line cannot pass each other. This proposal appears to have the same history in practice as the Rogers and Standal patents.
Russian Pat. No. 434,918 of 1974 discloses what is intended to be an apparatus for continuous supply of water from a main line to a sprinkler line but the apparatus is obviously inoperative and is inherently unstable.